Probably best to ask the other guys if they have already dug into the game and figured out how it works.
Generally PC games work much the same as consoles in that they can do what they like, however encryption is a far greater problem on PC games where things get encrypted fairly routinely actually where it is incredibly rare on consoles.
You still get tables (though common encodings are more common on PC), pointers and alternatives to those, compression, formatting/markup and all the rest to handle.
For a basic first pass many would try using a relative search tool. In the case of Spanish probably want to avoid any sentences that use accented or whatever characters but if using English as a base then you tend to avoid that one.
http://www.romhacking.net/utilities/513/ is a good start for a relative search tool.
If you want to learn about compression then I would usually point people at
https://ece.uwaterloo.ca/~ece611/LempelZiv.pdf
If the text is in the exe file (not a great thing to do as a programmer but ROM hacking deals with what is, not what should be) then you might have a packed exe (plus any protections) so you might want to look into executable unpacking.
